日期:2020-11-02 13:29:16
点击:59
内容简介:现整理解法如下: 数据样本: create table tx( id int primary key, c1 char(2), c2 char(2), c3 int ); insert into tx values (1 ,'A1','B1',9), (2 ,'A2','B1',7), (3 ,'A3','B1',4), (4 ,'A4','B1',2), (5 ,'A1','B2',2), (6 ,'A2','B2',9), (7 ,'A3','B...